Manifestation of localization of single particle states in low-dimensional
quantum systems has always been in limelight of research in condensed
matter physics since its prediction. Studies on this topic was basically
stimulated after the work of Anderson in 1958 [1]} which has
become a milestone in material science. It is well set that exponentially
localized states are the only allowed solutions for one-dimensional (1D)
systems with random on-site potentials [1]}, [3]}. Apart from
the above mentioned fact, another kind of localization phenomenon, the
so-called Wannier-Stark localization [4]}, has also drawn
much attention of many physicists [5]}, [6]}. This
type of localizing behavior is observed in 1D systems subjected to an
external electric field, even in absence of any kind of disorder. Although
the existence of localized surface states in crystals has been first
suggested by Tamm [7]}, on the basis of a special 1D model proposed
by James [8]}, popularity of this phenomenon among scientists has
been started to grow following the work of Wannier [4]} which
has won its way after the widespread application to the optical properties
of quantum wells [10]}, [11]}.
